Molding conduits



June 1 9, 192s. 1,674,445

T. E. MURRAY MOLDING CONDUITS Filed July 11, 1925 Kyi HUI

mw u 25 22 W MW cl WW v 57 nvmboz Patented .lune 19, 1928.

if f i THOMAS E. MURRAY, OF BROOKLYN,NEW YORK.

MOLDING CONDUITS.

Application led July 11, 1925. Serial No. 42,902.

In'certain previous applications I have described the molding of conduits, especially of underground conduits, with the aid of cores of rubber. The present invention provides improvements in apparatus of this class' and applicable generally to the molding of conduits of concrete and similar plastic material. f

The accompanying drawings illustrate an embodiment of the invention.

Fig. 1 is a longitudinal sectional viewY of the apparatus in use;

Figs. 2 and 3 are cross-sections of the same on the correspondingly numbered lines.

Fig. 4 is a sectional view of a modification.

The purpose of the invention is to lay a conduit 1 of concrete having longitudinal ducts 2 therein. Two such ducts are illustrated, but the invention may be applied to the making of a single duct or a greater number of ducts. A trench is dug with side walls 3 far enough apart for the easy introduction of the apparatus, and as the conduit is completed and the apparatus withdrawn, f

the sides of the trench'are filled in with earth 4 or other filling material embracing theV conduit. Afterwards, of course, the trench is filled up to the street level.

The apparatus comprises va pair of side members 5 of channel shape'resting on the bottomv of the trench and connected at intervals by cross-braces 6 and 7. A portion of the space between the side members is covered by a top plate 8, which may be hooked over the flanges of the side members as illustrated in Fig. 3. Fitting loosely between the side plates is a ram 9 connected by links 10 to thc sides of a yoke 11 which are piv` oted at their lower ends 12 to the side members 5, the yoke having an upwardly projecting handle 13. By operating the handle the ram can be reciprocated.

Passing freely through openingsin the cross plates 6 and 7 and the ram 9 are metal tubes 14. The upper one has an upwardly projecting handle 15 and has on its lower side a tooth 16 located between teeth 17 of the lower tube 14. When the handle 15 is rocked, therefore, both tubes 14 will be rocked. 4

Located within the tubes 14 are tubes 18 of rubber with thick walls and of such high grade composition that they can by a relative lengthwise movement in the concrete be-given such a tensile strain as to contract them suciently to separate them from the surrounding concrete ,wall and to pull them out and leave the completely formed ducts. The forward ends of the rubber tubesV are clamped by rings 19 von to hubs 2O carried bythe vertical portion 21 of a bracket 22 fastened on the rear plate ofy the appa` ratus.

Passing through each of the rubber tubes 18 isa rod 23 which extends tol the rear to a point beyond the end of the rubber tube and vcarries there a smoothing or trowelling device. AThis consists of a pair of segments 24 pivoted to the end of the rod 23,` held apart at their free ends by* a spring 25 and limited in their outward movement by ya bolt 26 passing freely through ears on the segments. 23 pass through bosses in the part 21 of the bracket and carry pinions 27 which are in engagement with each other and one of which has 'a handle 28 b-y which it can be V rocked or rotated.

The apparatus is operated inthe following way. The completed conduit vis shown at 1. The trowelling apparatus and the ends of the rubbertubes lie in the forward end thereof. A yuantity offresh concrete 29 has been poure in the space between the completed conduit 1 and the ram 9 while the latter was in the forwardposition. The

handle 13 of theyoke has been pushed to the rear and the ram moved back,fcompact ing the concrete 29v andjcausing it to perfectly lill the space betweenthe sidesof the The forward ends of the rods yso apparatus, and at the same-time forcing the apparatus forward. This operation is repeated at brief intervals and at a rate which is limited only by the rapidity of pouring of the concrete. Even when comparatively soft, it will hold its shape because of the lateral support of the filling '4, Fig. 3. Thus a practically continuous concrete structure is produced. The bore of the ducts `is formed about the rubber cores 18; the tube 14`being drawn out of the concrete while it is still soft enough to settle itself about the rubber cores. The rods 23 may have additional bearings in the rubber tubes as indicated in dotted lines at 30. As the appara tus is withdrawn the crank handle 28 is turned or rocked so as to produce a rotary smoothing or trowelling eect in addition to the longitudinal smoothing motion. The

tubes 18 leave a very smooth bore in the yducts when they are withdrawn if the con-V crete is sufficiently hard to hold its shape. But Where the apparatus is to be advanced rapidly, the concrete may-be sosoft beyond the ends of the tubes as to require a further smoothing by the segmental trowels. The

steel tubes 14 may be loosened before each.

advance of the machineV by rocking the handle 15. orf', this may be done during an advancing mevement- T lie apparatus maybe used in a similar. Way.A formolding COnClUDS. aboveground and in. Vvarious locations where. they .areV to be used and also for molding conduits in lengths or sections which are to be trans- Vported to the place of use. Y

Various other styles of troweling devices.Vv may be used for engaging the walls of the l ducts at the rear endy oi the core. Fig. il shows a modificationin thisrespect. The rubber tubes 18 are provided with trowels mounted directly on their rear ends. Such trowelsare composed oi'itwo approximately semi-circular. segments 31 of thin. steel cemented on to, the endoieach tube, the lea-tf ter being slittedas at SQbetween the edges of.Y the segments. As the cores are withdrawn from the freshly made concrete the resiliencyl of; the rubber will spread the troweling segments 31 against the surfacev of the surrounding concreteso asto smooth it.

. The resiliency of the rubbermay be supp-lementedfby coil springs 33, or. the springs may be'relied onsolely'to press the trowel.- ing segments outward.

Various modilications of the apparatus illustrated and, described may bev made byy those skilled in the art without departure from the invention as definedinthe following'elaims.

What Iclaim is:

1. Anapparatus for molding a duct in' plastic material .comprising ay core which is removable in aY straight longitudinal direc.- tion and atrowelingv device adapted to;l exert tion and-a troweling ldevice adapted'toexertl a. yielding pressure against the tacey of the duct, an operating rod for said troweling devise extending through Said core and means for giving a rotary movementto said rod.

l. An apparatus for molding a. duct in plastic. materalfomprsnsa-ser@ 0f rubber, means for exert-inge` lengthwisegpull on'the core to, contract itand reeit and to Withdraw itk from the sur-roundingmaterial and av troweling device adapted to smooth the face of the duct at the end of the core.

.5. An apparatus for molding a duct in plastic material comprising. a.. core of rubber,Y

means for. exerting a lengthwise pull on the core to contract it and freeit andfto withdraw it from the surrounding material and a. troweling device at the end of the core exerting a yielding lpressure against the face oil-the duct. Y

6.w An apparatus for molding a ductin plastic material comprising acore of rubber,A meansfor enertinga lengthwise pull on thence/re to contract it and i'reev it and to withdraw it fromthe surrounding materialV anda troweling device adapted to smooth theface of the duct at the end ofthe core and meansfor. giving a.. rotary movement to said trowelling dev-ice.V

In Witness whereof, I haye hereunto signed myname.

' THOMAS n. MURRAY. 

